1. Field of the Invention
The present invention relates to rotary electronic components used for configuring an input device for electronic equipment.
2. Background Art
A conventional rotary electronic component is described below, taking a rotary encoder as an example of a general structure, with reference to drawings.
FIG. 7 is a sectional view and FIG. 8 is an exploded perspective view of a conventional rotary encoder.
In FIGS. 7 and 8, case 1 made of insulating resin has a box shape with an open top. Round hole 1A is created at the center of its concavity. Multiple fixed resilient contacts 2 are fixed to the bottom of case 1.
The other ends of fixed resilient contacts 2 are led out from the side of case 1 as terminals 2A.
Flat strips of these fixed resilient contacts 2 before being bent are fixed to case 1 by insert resin molding. Then, fixed resilient contacts 2 are bent to a predetermined shape inclining upward in window 1B (FIG. 8) created at the bottom of the concavity.
In rotor 3 made of insulating resin, flange 3B is integrally molded to a lower part of roughly cylindrical operating knob 3A protruding upward. Cylindrical central protrusion 3C is rotatably fitted to round hole 1A on case 1. Central protrusion 3C is provided at the center of the bottom face of flange 3B. Rotary contact member 4 is also fixed to the bottom face of flange 3B housed in the concavity. This rotary contact member 4 is made of a metal sheet, is patterned to generate a predetermined encoder signal, and makes elastic contact with fixed resilient contacts 2.
Bearing 5 is attached to case 1. A middle part of operating knob 3A of rotor 3 is rotatably fitted to round hole 5A on this bearing 5. Resin cover sheet 6 is disposed underneath case 1 for covering round hole 1A and window 1B on case 1 so as to prevent dust from settling on the contacts inside case 1.
In the conventional rotary encoder as configured above, rotor 3 rotates when operating knob 3A is rotated. Rotary contact member 4, fixed to the bottom face of flange 3B of rotor 3, then rotates relative to each fixed resilient contact 2 such that predetermined encoder signals are achievable via each terminal 2A.
One of the prior-art documents related to this conventional rotary encoder is disclosed in Japanese Patent Unexamined Publication No. H11-273504.
In the above conventional rotary electronic component (rotary encoder), round hole 1A and window 1B, which are through holes, are created at the bottom of case 1, and are covered with cover sheet 6. This prevents dust from entering from the bottom. However, since a predetermined clearance is needed between operating knob 3A and hole 5A on bearing 5 in order to rotate operating knob 3A with a predetermined rotation force, it is difficult to prevent dust and moisture from entering inside to the contacts from the top.